When plural heat exchangers are arranged in a line with respect to an air flow direction (for example, referring to EP 859209 (corresponding to JP-A-10-111086)), an insulation gap is provided between a first heat exchanger core and a second heat exchanger core by plates disposed parallel to the air flow direction between the two heat exchanger cores. However, in this document, because the plates are disposed parallel to the air flow direction, it is impossible to increase quadratic moments of plate cross sections perpendicular to an axis parallel to the air flow direction. Therefore, the heat exchanger cores cannot be reinforced enough by the plates.
In contrast, if the plates are disposed nearly perpendicular to the air flow direction between the two heat exchanger cores, it is possible to increase quadratic moments of plate cross sections perpendicular to the axis parallel to the air flow direction without increasing a thickness of the plates. In this case, it is possible to reinforce enough the heat exchanger cores by the plates. However, a new problem as following is caused.
When the plates are disposed nearly perpendicular to the air flow direction, air cannot pass through portions where the plates are disposed between the two heat exchanger cores. Accordingly, if other heat exchanger is disposed at a downstream air side of the two heat exchanger cores, the other heat exchanger cannot be provided with enough air necessary for a heat exchange and cannot perform a sufficient heat exchange.